The present invention relates to an altitude compensation device for compensating for a change of air-fuel ratio of mixture supplied to an engine caused by a change in the altitude.
The density of air in the mixture sucked by the engine varies as the atmospheric pressure is changed, so that the air-fuel ratio of the mixture is undesirably changed to cause various inconveniences such as reduction of power, increase of noxious components and so forth.
Therefore, there has been proposed and actually used an altitude compensation device which compensates for the change of air-fuel ratio atributable to the change of atmospheric pressure due to a change in altitude.
In the conventional altitude compensation device, it is necessary to control a plurality of valves by a single altitude compensation device. For instance, in case of a 2-barrel 2-stage carburetor, it is necessary to provide compensation for the slow system, main system (first main jet, second main jet and power jet), vacuum for angle advancer of the distributor and so forth. It has, therefore, been attempted to provide a plurality of valves in contact with an end of a bellows so that these valves may be operated by a common bellows. However, such a bellows cannot be made perfectly free from vibration, and is usually subjected to the vibration caused by the engine, vibration of the chassis and so forth to cause oscillation or rocking up and down and to the left and right. The valves on the bellows are moved up and down as the bellows rocks and rolls. Thus, as the bellows is tilted, some of the valves are operated while the others are not, so that the altitude compensation device as a whole cannot perform the expected operation.